Once I splash the boat I'll measure it up - but having the mast and boom up is the key. The Bimini needs to clear the boom and be forward enough to clear the back of the boom.
I ended up putting the mast and boom up in the back yard. If i sit it on the high part of the cockpit side its 40 inches , if i go to the outer its 44 inches. I nended up buying a 46 inch high by 98 wide and 6 foot long . I shall move it around and alter the height as needed when it gets here. Just got to make sure i go foward enough to clean the main sheet when the boom goes out.
Dont suppose you have pictures of how your boom vang is set up ... when i bought the boat it doesnt seem to have the fittings for a vang.